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                  <p><small><a name="compression_archiving_definition"></a>PeaZip
is a free cross-platform file archiver and compression utility that
provides an unified
portable GUI for many Open Source technologies like 7-Zip, FreeArc,
PAQ, UPX... free alternative to WinRar, WinZip </small><small>and
similar
proprietary software</small><small>.<br>
- Create 7Z, ARC, BZ2, GZ, *PAQ, PEA, QUAD/BALZ, TAR, UPX, WIM, XZ, ZIP
files<br>
- Open and extract ACE, ARJ, CAB, DMG, ISO, LHA,
RAR, UDF, ZIPX files and more,</small><small> over 200 archive types
supported</small><small><br>
Features of PeaZip includes: </small><small> </small><small>archives
opener and extractor, </small><small>batch creation and </small><small>extraction
                  </small><small>of multiple
archives at once, </small><small>convert files, </small><small>create
self-extracting archives, split and join files,
strong encryption with two factor authentication, encrypted password
manager, </small><small>secure deletion, </small><small>find
duplicate files, </small><small>calculate hash and checksum,
export job definition as script.</small></p>
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            <td colspan="1" rowspan="1" style="vertical-align: top;"> <br>
            <h1 style="text-align: center;"><big><big><big><a
 name="data_compression_how_to"></a>How ZIP files work, compression
&amp; archiving definition</big></big></big></h1>
            <br>
            </td>
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            <div> </div>
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                  <td style="vertical-align: top;">
                  <ul>
                    <li>
                      <p><a
 href="what-is-zip-file.html#what_is_archive_file">HOW FILE
COMPRESSION AND ARCHIVING WORKS</a></p>
                    </li>
                    <li>
                      <p><a
 href="what-is-zip-file.html#what_is_zip_rar_file">WHAT IS A
COMPRESSED ARCHIVE FILE</a></p>
                    </li>
                  </ul>
                  <p> </p>
                  </td>
                  <td style="vertical-align: top; width: 128px;">
                  <h2><img alt="what is file compression"
 title="Compressed archive definition"
 src="file-format/archive-manager.png"
 style="width: 96px; height: 96px;" align="right"></h2>
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 style="background-color: rgb(255, 255, 255); vertical-align: top;">
            <div style="text-align: left; color: rgb(0, 0, 0);">
            <h2><big><big><big><a name="what_is_archive_file"></a><a
 href="what-is-zip-file.html#data_compression_how_to">How file
compression and archiving
works</a></big></big><br>
            </big></h2>
            </div>
            <br>
            <h3><big><span style="font-weight: bold;">File archiving
definition</span></big><span
 style="font-weight: bold; background-color: rgb(255, 255, 204);"></span></h3>
            <span
 style="font-weight: bold; background-color: rgb(255, 255, 204);"></span><br>
            <span
 style="font-weight: bold; background-color: rgb(255, 238, 221);"><br>
            <a name="what_is_file_archiving"></a>File
archiving</span><span style="background-color: rgb(255, 238, 221);">
means
to combine multiple files together for easier management of the data</span>
(i.e. backup, mail attachments, sharing by FTP, torrent, cloud, or any
kind of network service, etc) as for the host filesystem all the data
will be treated as a single file rather than as multiple ones,
eliminating the overhead of handling multiple objects - for each single
file, locating the physical data on disk, locating possible fragments,
checking file level security permissions, and so on.<br>
            <table style="width: 100%; text-align: left;" border="0"
 cellpadding="24" cellspacing="0">
              <tbody>
                <tr>
                  <td
 style="vertical-align: top; text-align: right; width: 128px;">
                  <h2><span style="font-weight: bold;"><img
 title="How file archiving works" alt="how file compression works"
 src="file-format/quotes.png" style="width: 32px; height: 32px;"></span></h2>
                  </td>
                  <td style="vertical-align: top; font-style: italic;"><a
 name="first_archive_formats"></a>The idea of archiving
files pre-dates .zip format by many years, as in
AR Unix
format (later superseded by TAR, released in 1979 and
standardized in 1988), and LBR format in
CP/M / DOS world in early '80s.</td>
                  <td style="vertical-align: bottom; width: 128px;">
                  <h3><img title="How data compression works"
 alt="how file archiving works" src="file-format/quotes-inverse.png"
 style="width: 32px; height: 32px;"></h3>
                  </td>
                </tr>
              </tbody>
            </table>
            <br>
            <h3><big><span style="font-weight: bold;">File compression
definition</span></big></h3>
            <span
 style="font-weight: bold; background-color: rgb(255, 238, 221);"><br>
            <a name="whant_is_file_compression"></a>File
compression</span><span style="background-color: rgb(255, 238, 221);">
means to reduce size of data on disk encoding it to a smaller output</span>,
employing various strategies to efficiently map (most cases of) a
larger input to a smaller output, i.e. using statistical analisys to
reduce redundancy in inputa data.<br>
Data compression,
too, predates development of ZIP standard, as once the input files were
merged into a single output archive, the operation was often
concatenated to lossless data compression to reduce the size of the
archive using various utilities available at the time as SQ (DOS,
CP/M), CRUNCH (CP/M), and compress (Unix).<br>
TAR format, for example, is still an uncompressed archive standard, and
uses external compressors, nowadays usually GZ (fast deflate based
compression, same as in ZIP format), BZ2 (more powerful compression),
XZ (modern, very powerful LZMA based compression - the default
compression algorithm used in 7Z format), BR Google's Brotli (modern,
very fast compressor), and ZST Facebook's Zstandard (another modern,
very fast compressor).<br>
            <br>
Learn more about similarities and differences in <a
 href="lossless-compression-lossy-compression.html">Lossless data
compression and Lossy data
compression</a>. For general purpose compressed archive file,
however, compression means Lossless Compression, a 1:1 mapping of input
to a smaller output.<br>
            <br>
            <a name="history_of_file_compression"></a>SEA's ARC format
(1985) combined the archival and (lossless)
compression in a single pass, providing probably the first example of
general purpose of archive manager, which allowed both to spare storage
for backup, and save upload
and download bandwidth (and time) for sharing - at the time, mainly BBS.<br>
A few years later, after a controversy with SEA about
alleged derived
work in PKARC, Phil Katz superseded previous works releasing PKZIP,
which knew great success due multiple factors, as superior speed and
efficiency, and being the specs released under public domain, and
having relatively few competitors in years of fast PC market expansion.<br>
            <div style="text-align: left;"> </div>
            <div style="text-align: left;"> </div>
            <div style="text-align: left;"> </div>
            </td>
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        </tbody>
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 style="background-color: rgb(240, 240, 240); width: 960px; text-align: left;"
 border="0" cellpadding="24" cellspacing="0">
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            <td
 style="background-color: rgb(255, 255, 255); vertical-align: top;">
            <div style="text-align: left; color: rgb(0, 0, 0);">
            <h2><big><big><big><a name="what_is_zip_rar_file"></a><a
 href="what-is-zip-file.html#data_compression_how_to">What are
compressed archive files</a></big></big><br>
            </big></h2>
            </div>
            <br>
            <h2><big><span style="font-weight: bold;">What is and how a
ZIP file works</span><br>
            </big></h2>
            <br>
            <a name="classic_archive_formats"></a><a
 href="zip-file-format.html">ZIP format</a>
is a <span style="font-weight: bold;">lossless data
compression and archival format</span> created in 1989 by Phil Katz,
implemented for the first time in PKWARE's PKZIP.<br>
            <a name="wwhat_are_zip_files"></a>The ZIP file format
specifications were released under public domain
and the format had long and lasting success, to the point often "zip"
is colloquially used for any generic compressed archive, and many
package formats are based on deflate compression and/or same or very
similar specs: Java JAR / WAR / EAR, Android APK,
Apple iOS IPA files (iPhone and iPad devices), Microsoft CAB and Office
compound files.<br>
            <span class="st"><a name="what_is_a_zip_file"></a>WinZip
12.1 (2009) introduced the new <span style="font-weight: bold;">ZIPX </span>file
format specifications
for identifying a
new archive standard which
supports newer and more powerful compression algorithms.<br>
            <br>
            </span>
            <h3><big><span style="font-weight: bold;">What are and how
RAR,
ACE, 7Z files work</span><br>
            </big></h3>
            <br>
            <a name="modern_archive_formats"></a>During '90s and
beyond, multiple alternative archival standard emerged,
as <span style="font-weight: bold;">ARJ</span>, <span
 style="font-weight: bold;">RAR</span>
(1993), <span style="font-weight: bold;">ACE</span>,
and <span style="font-weight: bold;">7Z</span>
(1999), introducing unique
features to
distinguish
them from the growing number of competitors, in example:<br>
            <ul>
              <li>usually, stronger compression ratio than ZIP at the
cost of slower operation - but that disadvantage would have been paid
off by slower transfer time (especially on slow and public networks)
of smaller output file<br>
              </li>
              <li>multi volume archival, splitting the output to met
constrains as mail attachment size limit</li>
              <li>encryption, to enforce end user's privacy if the file
is stolen, or
passed through unsecure servers (unencrypted public network, or any
third party controlled channel as a mail server, or remote storage
service)</li>
              <li>error detection and correction, to prevent extraction
in the event data gets corrupted (i.e. faulty connection, damaged disk)
and attempt recovery from known good data.<br>
              </li>
            </ul>
Archival file format tends to be more geared towards powerful,
computing intensive features to enhance manageability of data (high
compression, strong encryption), rather than enhancing ability to work
on live data (rapid read and write access) like filesystems, even if
some archive management utilities offers various mechanisms to <a
 href="add-remove-files-from-archive.html">add or remove data inside
archives</a>, and <a href="how-to-update-existing-archive.html">update
or sync files already in the archive</a>.<br>
More choice in standards brought users more features and healthy
competition between standards (see <a
 href="archive-file-formats-comparison.html">comparison of archive
formats</a>) and implementations, but also brought
the need for
flexible multi-purpose archival applications, like PeaZip, to deal with
different formats users may encounter, and to make full use of the
feature's potential of
the different supported file formats.<br>
In recent years the trend is shifting toward very fast and highly
efficient compression algorithms, aiming to minimize the compression
and decompression overhead in data transmission and achieve near
real-time speed, with algorithms like Google's <span
 style="font-weight: bold;">Brotli </span>(<a
 href="brotli-compressed-file-format.html">BR file format</a>) and
Facebook's <span style="font-weight: bold;">Zstandard </span>(<a
 href="zst-compressed-file-format.html">ZST file format</a>).<br>
            <table style="width: 100%; text-align: left;" border="0"
 cellpadding="24" cellspacing="0">
              <tbody>
                <tr>
                  <td
 style="vertical-align: top; text-align: right; width: 128px;">
                  <h2><span style="font-weight: bold;"><img
 title="Definition of file archiving and compression"
 alt="what are archive files" src="file-format/quotes.png"
 style="width: 32px; height: 32px;"></span></h2>
                  </td>
                  <td style="vertical-align: top; font-style: italic;">Definition
of compressed / archive file is broadening, with package and
disk image format standards implementing native compression (in some
cases even encryption) features - Microsoft CAB and WIM, Apple DMG.</td>
                  <td style="vertical-align: bottom; width: 128px;">
                  <h3><img title="Definition of file archival"
 alt="what are compressed files formats"
 src="file-format/quotes-inverse.png" style="width: 32px; height: 32px;"></h3>
                  </td>
                </tr>
              </tbody>
            </table>
            <a name="how_rar_files_works"></a>More online
resources about file archiving and compression formats: <a
 target="_blank" href="https://en.wikipedia.org/wiki/Ar_%28Unix%29">AR<img
 alt="AR wiki" title="Wikipedia: AR file format"
 src="free-rar/extractor.png"
 style="border: 0px solid ; width: 12px; height: 10px;"></a> (Unix), <a
 target="_blank"
 href="https://en.wikipedia.org/wiki/LBR_%28file_format%29">LBR<img
 alt="wikipedia lbr file" title="LBR format"
 src="free-rar/extractor.png"
 style="border: 0px solid ; width: 12px; height: 10px;"></a> (CP/M), <a
 target="_blank"
 href="http://www.bbsdocumentary.com/library/CONTROVERSY/LAWSUITS/SEA/">SEA<img
 alt="sea pkware controversy" title="ARC vs ZIP"
 src="free-rar/extractor.png"
 style="border: 0px solid ; width: 12px; height: 10px;"></a> company, <span
 class="st"><a target="_blank" href="http://kb.winzip.com/kb/entry/7">WinZip's
ZIPX
standard<img title="ZIPX Knowledge Base entry"
 alt="winzip's zipx standard" src="free-rar/extractor.png"
 style="border: 0px solid ; width: 12px; height: 10px;"></a>, </span><a
 target="_blank" href="https://github.com/google/brotli">Google Brotli<img
 title="Google Brotli project page" alt="Brotli fast compression"
 src="free-rar/extractor.png"
 style="border: 0px solid ; width: 12px; height: 10px;"></a>, <a
 target="_blank" href="https://facebook.github.io/zstd/">Facebook
Zstandard<img title="Facebook's ZSTD project page"
 alt="Zstandard fast compression" src="free-rar/extractor.png"
 style="border: 0px solid ; width: 12px; height: 10px;"></a> project
pages.</td>
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COMPRESSION DEFINITION</a><br>
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            <p><a href="peazip-help-faq.html">FAQ</a>
&gt; Archiving &gt; What is a compressed "zip" archive file<br>
            </p>
Topics and search suggestions about how 7Z, ACE, RAR, TAR, ZIP, ZIPX
files work, how data compression and archiving works, definition of
archive files, what are zip files and most common compressed archives
formats
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                  <td
 style="vertical-align: top; width: 25%; font-style: italic;"> how data
compression works, <br>
                  <h3>how zip files work,</h3>
file archival definition,<br>
how data is compressed,<br>
definition of file archiving,<br>
free zip file archiver,<br>
what are zip files,<br>
zipping files and folders,<br>
what are archive of files,<br>
                  </td>
                  <td
 style="vertical-align: top; width: 25%; font-style: italic;"> how file
compression works, <br>
how rar files work, <br>
how 7z files work,<br>
zip file definition,<br>
                  <h3>what is a zip file,</h3>
definition of file compression,<br>
zip file archiving software,<br>
what is zip format,<br>
what is a 7Z, RAR, TAR, ZIP file<br>
                  </td>
                  <td
 style="vertical-align: top; width: 25%; font-style: italic;"> how file
archiving works,<br>
what is a compressed file,<br>
how archive files work,<br>
what is a zipped file,<br>
what is an archive file,<br>
                  <h3>definition of zip file,</h3>
how file archival works,<br>
what is rar file format,<br>
what are archive file formats,<br>
                  </td>
                  <td
 style="vertical-align: top; width: 25%; font-style: italic;">what are
file archives,<br>
file compression definition, <br>
how ace files work, <br>
how to uncompress files, <br>
how tar files work,<br>
free file zipper utility,<br>
what is a zip archive,<br>
what is file archiving definition,<br>
definition of archive files<br>
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